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Questions and Answers
What is the primary focus of process geomorphology?
What is the oldest year-by-year record of geomorphic processes?
When did geomorphologists begin to direct process studies towards the construction of models for predicting short-term changes in landforms?
What is the primary goal of modeling geomorphic processes?
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What is the significance of the flood levels of the River Nile in Lower Egypt?
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What is the focus of process studies and global environmental change?
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When were the first efforts made to measure weathering rates?
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What is the significance of the transport of debris by running water?
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What is the focus of geomorphologists in the modern era?
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What is the significance of the rates of modern denudation in some of the world’s major rivers?
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Study Notes
Stratigraphical Relationships and Chronologies
- Observed stratigraphical relationships provide relative chronologies, which are events placed in order of occurrence without accurately fixed dates.
- Absolute chronologies are derived from sequences dated using historical records, radiocarbon analysis, dendrochronology, luminescence, paleomagnetism, and more.
Quaternary Geomorphology
- Environmental changes over the last couple of million years have led to significant adjustments in many landforms and landscapes.
- Climatic swings from glacial to interglacial conditions have altered geomorphic process rates and regimes in landscapes, causing disequilibrium and increases in geomorphic activity.
- These changes resulted in the reshaping of hill slopes, reworking of regoliths, and changes in sediment stores in valley bottoms.
Long-term Geomorphology
- Studies of landforms and landscapes older than the Quaternary or late Quaternary period are called long-term geomorphology.
- Long-term geomorphology depends on landform analysis and relative dating, as most absolute dating methods fail for the timescales of interest.
- Accurately dating long-term development landforms is challenging, and later processes often alter or destroy them.
Historical Geomorphology
- All landforms have a history, but some, like ripples on beaches, are short-lived and often unrecorded.
- More persistent landforms at various scales, such as coastal features, landslides, and river terraces, provide clues to past processes and events.
- Historical geomorphology focuses on understanding landscape history by mapping morphological and sedimentary features.
Foundations of Historical Geomorphology
- Historical geomorphologists traditionally worked to understand landscape history by mapping features and using the dictum that "the present is the key to the past".
- This approach assumes that the effects of geomorphic processes seen today can be used to infer causes of landscape changes in the past.
Process Geomorphology
- Process geomorphology is the study of the processes responsible for landform development.
- It involves measuring and modeling geomorphic processes, such as fluvial processes, to understand landform development.
Measuring Geomorphic Processes
- Some geomorphic processes have a long record of measurement, such as flood levels of the River Nile and sediment carried by the Mississippi River.
- Measurements of weathering rates, dissolved load of rivers, and chemical denudation rates have been made over the years.
Modeling Geomorphic Processes
- Since the 1960s and 1970s, geomorphologists have directed process studies towards constructing models for predicting short-term changes in landforms.
- These models draw on soil engineering, hydraulic engineering, and other fields to understand and predict geomorphic processes.
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Description
Understanding stratigraphical relationships and chronologies in geomorphology, including Quaternary and long-term geomorphology. Learn about relative and absolute chronologies, and their applications.
